This whole multiverse concept is like plot armor, but for the writers/editors. A lot of these characters are decades old, you can't re-tell the same story, especially origin stories, over and over, or if there's a new twist to a familiar story, or a character gets killed off and later writers/editors look back in hindsight and say "Hmmmmm.... we really shouldn't have done that, or a writer simply goofs up and forgot some details from a character's past....... they can just say this is a different timeline and there are an infinite number of timelines. Those little things aren't really mistakes....... they're "features" of a multiverse.